What Are Our Concerns About Bearings（21）

Q1:What is the meaning of 6208-ZZ bearing model?  

The exact model is 6208-2Z, which means: deep groove ball bearing, light narrow

series, inner diameter 40, outer diameter 80, thickness 18, 2Z means double-sided dustproof seal cover 

Q2:What is DU bearing?  

DU appears in many places on bearings, mainly depends on your bearing brand.

Let me give you an example.  

French SNR bearing supplementary code DU means general installation in pairs;  

(Can be paired freely)  

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French SNFA bearing supplementary code DU represents universal pairing, which   means that bearings can operate normally if they need to be paired, face to face, back to back and in series, and have no effect. Generally, this code will appear    on angular contact ball bearings;  

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SKF bearing U(DU) — isoglapped angular contact ball bearing  

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Japanese seiko NSK bearing  

D or DU refers to a non-contact rubber dust cover for a deep groove ball bearing  or angular contact ball bearing. The common model is 6205DU 5205DU  

If it is DDU, it means: deep groove ball bearing, angular contact ball bearing      double-sided non-contact rubber dust cover, the common model is: 6205DDU 5205DDU  

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Germany bearing  

DU stands for two sets of general combined configuration bearings (the same     meaning as the first and second interpretations)  

Q3:What is the bearing model with an outer diameter of 32.5mm and an inner    diameter of 15mm?  

Name = Angular contact ball bearing  

Standard = extracted from GB/T 292-1994 refer to ISO15-1981  

Unit = (mm)  

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Bearing code =7002CJ  

Size \ d = 15  

Size \ D = 32  

Size \ B = 9  

Size \ rs (min) = 0.3  

Size \ r1s (min) = 0.15  

Weight (kg) material = 0.028  

Name = Angular contact ball bearing  

Standard = extracted from GB/T 292-1994 refer to ISO15-1981  

Unit = (mm)  

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Bearing code =7002ACJ  

Size \ d = 15  

Size \ D = 32  

Size \ B = 9  

Size \ rs (min) = 0.3  

Size \ r1s (min) = 0.15  

Weight (kg) material = 0.028  

Q4:What is the inner diameter of bearing form 30211?  

30211  

Tapered roller bearing  

The last two times 5 is the inner diameter of the bearing  

30211 should have an inside diameter of 55  

Bearings can choose to use Taiwan ZNQ  

Quality can replace imported products with high cost performance

Q5:What are the reasons for the high temperature of motor bearings?  

• 1. Too much or too little grease;  
• 2. The oil is not good and contains impurities: check whether there are impurities  in the oil and replace the clean grease.  
• 3. The inner and outer parts of the bearing are too tight: when the bearing is too loose, the agricultural machinery 2 # adhesive or low temperature iron plating is   used. When the bearing is too tight, the shaft journal shall be properly trimmed to meet the tolerance requirements.  
• 4. Oil seal is too tight: replace or repair the oil seal.  
• 5. Eccentric bearing cover, rubbing with the shaft: repair the bearing inner cover to make the clearance with the shaft appropriate.  
• 6. The two side end covers or bearing covers of the motor are not mounted flat:   install the end covers or bearing covers into the stopper according to the correct  process, and then evenly tighten the screws.  
• 7. Bearing failure, wear, sundries, etc. : Replace damaged bearings, bearings containing impurities should be thoroughly cleaned and oil changed.  
• 8. The connection between the motor and the transmission mechanism is eccentric or the transmission belt is too tight: calibrate the center line of the connection     between the motor and the transmission mechanism, and adjust the tension of the transmission belt:.  
• 9. Select small bearing type, overload, so that the rolling body bears too much load: select the appropriate bearing type.  
• 10. Bearing clearance is too large or too small: replace the new bearing.  
• 11. The sliding bearing oil ring is not flexible in rotation: repair the oil ring to     make the size of the oil ring correct and correct the balance.  

Q6:Bearing thickness tolerance  

Please refer to GB/T307.1-94 0, rolling bearing radial bearing tolerance  

Q7:How to calculate bearing specifications according to bearing type?  

1. Bearing type representation: Code (fourth digit from right)  

• 0: deep groove ball bearing  
• 1: self-aligning ball bearing  
• 2: cylindrical roller bearings  
• 3: self-aligning roller bearing  
• 4: needle roller bearings  
• 5: spiral roller bearings  
• 6: Angular contact ball bearing  
• 7: tapered roller bearings  
• 8: thrust ball bearing thrust angular contact ball bearing  
• 9: thrust cylindrical roller bearing thrust self-aligning roller bearing thrust needle    roller bearing thrust tapered roller bearing  

2.  Bearing dimension representation  

Diameter series, code (third digit from right)  

Ultra light: 7 cases: 1000700  

Ultra light: 8 and 9 cases: 7000800 7000900  

Extra light: 1 7 cases: 7000100 7002700  

Light: 2 cases: 3056200  

Chinese: 3 cases: 300  

Weight: 4 cases: 2086400  

Width series, code (seventh digit from right)  

Narrow: 7 cases: 7000800  

Normal: 1 case: 1000700  

Width: 2 cases: 2007900  

Extra-wide: 3 cases: 3000700  

Example: 4774900  

Height series, code (seventh digit from right)  

Extremely low: 7 cases: 7589900  

Low: 9 cases: 9008900  

Normal: 1 example: 1008900  

3, bearing inner diameter representation  

Bearing standard inner diameter: 10  

01 Inner diameter: 12  

02 INSIDE diameter: 15  

03 Inner diameter: 17  

Number *5= Inner diameter Example: 205: Inner diameter 25, 206, 30  

Bearing code is read as:  

Lead code: Bearing clearance, bearing tolerance class  

Code number right number:  

7: Width series  

6.  5: Bearing structure form  

Type 4:  

3: Diameter series  

2,1: bearing inner diameter  

Example: 3G3053220, that is, radial clearance according to the third group, class   G tolerance, tolerance grade according to the letters B, C, D, E, G, in order from  high to low tolerance grade.  Class G is generally omitted in the bearing code  

6305,6 means thrust angular contact ball bearing, 3 means medium series, 05     means inner diameter, 5 times 5, inner diameter is 25